Download Atomic Structure – Revision Pack (C4) Atoms: A nucleus is made up

Atomic Structure – Revision Pack (C4)
Atoms:
A nucleus is made up of neutral neutrons and positive protons. The nucleus is
surrounded by negatively charged electrons. The nucleus is positive but the atom
has no overall charge because the protons and electrons cancel each other out.
Subatomic
particle
Relative charge
Relative mass
Proton
+1
1
Neutron
0
1
Electron
-1
0.0005
Element – made up of one type of atom; cannot be chemically broken down
Compound – made of two or more elements that are chemically combined
Mass and Atomic Number:
19
9
The mass number is the larger number of the two. It represents how
many neutrons and protons there are in the atom.
F
The atomic number is the smaller number of the two. It represents
how many protons there are in the atom. The number of protons is
equal to the number of electrons.
An atom is neutral because it has the same number of protons as
neutrons; the positives cancel out the negatives.
The number of neutrons is equal to the mass number take away the atomic number.
Arrangement of electrons:
The elements of the periodic table are arranged in order of increasing atomic
number.
The amount of electrons is different for the shells of an atom:
The maximum number of electrons for the first shell is 2.
The maximum number of electrons for all of the shells from then is 8.
Na (shown to the left) has an electronic structure. This is 2.8.1 – two
electrons in the 1st shell, 8 in the 2nd and 1 in the 3rd. The number of
electron is equal to the proton number; so 2 + 8 + 1 = 11 which is the
atomic (proton) number of sodium (Na).
Atomic Structure – Revision Pack (C4)
Groups and Periods:
Periods =
rows =
number
of
occupied
shells
Groups = columns =
number of electrons on
outer shell
Isotopes:
Isotopes are elements that have the same atomic number, but differing mass
numbers; this means that they have different numbers of neutrons.
Isotope
Electrons
Protons
Neutrons
3
3
3
3
3
4
3
3
5
The different number of neutrons
can be deduced, as with these
lithium isotopes.
Developing the Theory:
John Dalton created the original theory, which was provisional meaning it could be
changed later. The theory was later confirmed by better evidence.
J.J. Thompson, Rutherford and Bohr all found new evidence that changed the
explanation of the model of the atom. With later evidence their predictions were
confirmed.
Unexpected results also change ideas rapidly. For example, Geiger and Marsden
had some unexpected results which made significant contributions to the ideas of
Rutherford and Bohr.
Atomic Structure – Revision Pack (C4)
Past Papers:
PPQ(1):
OCR Gateway June 2013 C4 C5 C6
PPQ(2):
OCR Gateway June 2013 C4 C5 C6
PPQ(3):
OCR Gateway June 2013 B4 C4 P4
Atomic Structure – Revision Pack (C4)
Mark Schemes:
PPQ(1):
PPQ(2):
PPQ(3):